Art is generally a very quiet dog. He never makes any noise when playing with other dog, he tells them when it's too much by biting at them not to hurt but to make them back off, but there is no growling/barking/etc. He only barks/howl/thing when he see's something that is not right. Like if someone is outside that should not be there, or if something like a balloon is there when it was never there before kind of thing. The thing is, it is an ear piercing (not high pitch just sudden and loud!) "ROOOOOOOOO!" It is so sudden and almost looks painful for him to do. He literally strains to PUSH it out of him! He never barks, it is always that sudden "ROOOO!" thing. I think he doesn't bark/make sounds because it really does look like he has to force the noise out. Anyone have a dog like this?